This invention relates to a valve seat tool and method for removing and inserting valve seats, and more particularly to such a tool which is adapted to engage the valve seat for removal and insertion thereof, upon removal of the associated valve member from the valve body.
Heretofore, particularly for hand operated valves having a straight through flow passage, a valve seat having a pair of axially aligned ports therein for alignment with the flow passage has been provided and receives a valve member for blocking fluid flow through the flow passage.
The valve member may be a tapered plug member, for example, which is movable upon rotation of a valve stem between an extended position blocking fluid flow through the flow passage and a retracted position permitting fluid flow through the flow passage. The valve seat or seat insert is preferably of a frusto-conical shape formed of a soft non-metallic material such as a resilient plastic material, for example, or formed of a metallic material, such as stainless steel, for example.
The seat is normally mounted within a cavity in a valve body with a press friction fit and to remove the seat for repair or replacement, a punch or screw driver has been inserted within the flow passage from an end port or bonnet opening for prying the seat from its cavity. When the seat "snaps" free, the punch or rod may strike and damage the valve body portion about the flow passage at the seat.
Also, since the punch or screw driver is inserted within the flow passage which may be relatively long and of a relatively small diameter, it may be difficult under certain conditions to obtain sufficient leverage for prying the valve seat loose.